Development of a sandwich hybridization assay for the identification and quantification of red drum (Sciaenops ocellatus) eggs: a novel tool for fishery research and management

Abstract

Egg identification and quantification are crucial to understanding the spawning and recruitment dynamics of economically important fish species. This study describes the development of a novel molecular method for finfish egg identification that eliminates the need for time-consuming microscopy. Sandwich hybridization assay (SHA) uses two ribosomal RNA (rRNA)-targeted oligonucleotides to directly detect unpurified and unamplified rRNA. Probes were designed to complement the internal transcribed spacer (ITS) region of the red drum (Sciaenops ocellatus), an important recreational game fish for which spawning and reproductive information is sparse. Sample homogenization procedures were modified to disrupt egg chorion, and the resultant assay detected S. ocellatus eggs and tissues without cross-reactivity. Standard curves were linear (y450 = 0.001x + 0.054; R2 = 0.999), showing potential for quantitative uses, and the lower limit of detection was 5 eggs·mL−1 homogenate. Ontogenetic stage had a significant effect (ANOVA, p < 0.05) on optical density. The assay successfully detected S.ocellatus eggs in field samples from Charleston Harbor, South Carolina, and could be incorporated into current management practices or adapted to other species.